JPWO2016117706A1 - Hard coat film - Google Patents

Abstract

The present invention is a hard coat film in which a hard coat layer is provided on at least one side of a cycloolefin film via an easy-adhesion layer, and is excellent in adhesion over time under normal conditions and moist heat resistance, and under heat resistance conditions. A hard coat film free from cracks is provided. In the hard coat film (10) of the present invention, the hard coat layer (3) is provided on at least one surface of the cycloolefin film (1) via the easy adhesion layer (2). The easy-adhesion layer (2) contains a mixture of a polyolefin resin and a styrene acrylic resin, and their blending ratio (parts by weight) is, for example, in the range of 95/5 to 40/60. The hard coat layer (3) contains an ionizing radiation curable resin having a weight average molecular weight of 700 or more and 3600 or less.

Description

  The present invention relates to a hard coat film, and more specifically, flat panel displays such as liquid crystal display devices, plasma display devices and electroluminescence (EL) display devices, display device parts such as touch panels, and buildings, automobiles, and train windows. The present invention relates to a hard coat film in which a hard coat layer is provided via an easy-adhesion layer on a cycloolefin film that can be used as a protective film such as glass.

  A display surface of a flood panel display such as a liquid crystal display device (LCD) is required to be provided with scratch resistance so that the surface is not damaged due to scratches during handling. Therefore, it is generally performed to impart scratch resistance using a hard coat film in which a hard coat layer is provided on a base film. In recent years, with the spread of touch panels that can input data and instructions by touching with a finger, pen, etc. while viewing the display on the display screen, functional requirements for hard coat film having optical visibility maintenance and scratch resistance are It is growing.

Therefore, a cycloolefin film excellent in transparency, heat resistance, dimensional stability, low hygroscopicity, low birefringence, and optical isotropy as a base film is expected to be used for optical member applications. A hard coat layer is provided on a cycloolefin film. However, unlike an acrylic film or a polyester film, the cycloolefin film has a problem in that the adhesion between the base film and the hard coat layer is poor because the number of polar groups on the film surface is small.
Therefore, conventionally, methods for imparting easy adhesion with a hard coat layer to a cycloolefin film are disclosed in Patent Document 1, Patent Document 2, and the like.

JP 2001-147304 A JP 2006-110875 A

  Conventionally, Patent Document 1 discloses corona treatment, plasma treatment, UV treatment, and the like as methods for imparting easy adhesion with a hard coat layer to a cycloolefin film. Adhesion with the hard coat layer is insufficient, and there is a problem that adhesion failure with time tends to occur.

  Patent Document 2 discloses that an anchor coating agent made of an olefin resin is coated on a cycloolefin film. This anchor coat treatment improves the adhesion between the cycloolefin film and the hard coat layer to some extent, but in the anchor coat layer where the coating film is flexible and stretched and the hard coat layer where the coating film is hard and does not stretch, There was a problem that cracks (film cracks, cracks, etc.) were likely to occur on the surface of the hard coat layer due to the difference in shrinkage of both coating films under the conditions (for example, stored in a dryer at a temperature of 100 ° C. for 5 minutes).

  Therefore, in the conventional hard coat film, adhesion (particularly adhesion over time) with a hard coat layer when a cycloolefin film is used as a base material, and crack generation prevention under heat resistant conditions have been problems.

  Accordingly, the present invention is a hard coat film in which a hard coat layer is provided on at least one surface of a cycloolefin film via an easy-adhesion layer, and has excellent temporal adhesion under normal conditions and moist heat resistance, and is heat resistant. It aims at providing the hard coat film which does not generate | occur | produce a crack on conditions. Another object of the present invention is to provide a hard coat film that is curled and excellent in processing suitability.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by having the following configuration.
That is, the present invention has the following configuration.

  The first invention is a hard coat film in which a hard coat layer is provided on at least one side of a cycloolefin film via an easy adhesion layer, and the easy adhesion layer is a mixture of a polyolefin resin and a styrene acrylic resin. And the hard coat layer contains an ionizing radiation curable resin having a weight average molecular weight of 700 or more and 3600 or less.

  Moreover, 2nd invention is the said 1st invention. WHEREIN: The mixture ratio (weight part) of the said polyolefin resin and the said styrene acrylic resin in the said easily bonding layer is in the range of 95 / 5-40 / 60. It is a hard coat film characterized by being.

  Moreover, 3rd invention is the said 1st or 2nd invention. WHEREIN: The said ionizing radiation curable resin contains the polyfunctional acrylate which has a 3 or more (meth) acryloyloxy group in 1 molecule. It is the hard coat film characterized.

A fourth invention is a hard coat film according to any one of the first to third inventions, wherein the hard coat layer satisfies the following conditions.
Conditions: A film is formed on a polyethylene terephthalate film by forming a hard coat layer made of the above-mentioned ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² so as to form a 2 μm thick coating film. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation until cracks occur in the coating film is 8% or more and 45% or less.

  The fifth invention is the hard coat film according to any one of the first to fourth inventions, wherein the easy-adhesion layer has a thickness in the range of 0.1 μm to 1.0 μm. .

  According to the present invention, there is provided a hard coat film in which a hard coat layer is provided on at least one surface of a cycloolefin film via an easy-adhesion layer, which has excellent adhesion over time under normal conditions and moist heat resistance, and is heat resistant. A hard coat film free from cracks under the conditions can be obtained.

  Further, according to the present invention, it is possible to obtain a hard coat film that is further suppressed in curling and excellent in processing suitability.

It is sectional drawing which shows the layer structure of one Embodiment of the hard coat film which concerns on this invention. It is a figure for demonstrating the evaluation method of the curl height of a hard coat film.

Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not necessarily limited to the following embodiment.
In the present specification, “XX to ΔΔ” means “from XX to ΔΔ” unless otherwise specified.

  As shown in FIG. 1, the layer constitution of the hard coat film 10 of one embodiment of the present invention is such that the hard coat layer 3 is provided on at least one surface of a cycloolefin film 1 as a base film via an easy adhesion layer 2. The easy-adhesion layer 2 includes a mixture of a polyolefin resin and a styrene acrylic resin, and a hard coat layer containing an ionizing radiation curable resin is formed on the easy-adhesion layer 2. It is.

[Base film]
First, the base film of the hard coat film will be described.
In the present invention, as the base film of the hard coat film 10, a cycloolefin film excellent in transparency, heat resistance, dimensional stability, low hygroscopicity, low birefringence, optical isotropy, and the like is used. Features. Specifically, cycloolefin units are polymerized alternately or randomly in the polymer skeleton and have an alicyclic structure in the molecular structure, and include norbornene compounds, monocyclic cyclic olefins, cyclic conjugated dienes and vinyl fatty acids. A cycloolefin copolymer film or a cycloolefin polymer film, which is a (co) polymer comprising at least one compound selected from cyclic hydrocarbons, is selected and used as appropriate.

  Moreover, in this invention, although the thickness of the said cycloolefin film 1 is suitably selected according to the use for which a hard coat film is used, from the viewpoint of mechanical strength, handling property, etc., in the range of 10 micrometers-300 micrometers. It is preferable that it is in the range of 20 μm to 200 μm.

  In the present invention, when the heat resistance of the cycloolefin film 1 is used for a hard coat film, a thermogravimetry (TG) method for measuring a thermal change when a temperature change is applied to a sample or a differential scanning calorific value. The use of a film having a glass transition temperature measured by a measurement (DSC) method or the like of about 120 ° C. to 170 ° C. is preferred.

  In the present invention, when the cycloolefin film 1 is used for a hard coat film, a resin obtained by kneading a cycloolefin resin and an ultraviolet absorber is used in the form of a film for the purpose of preventing coating film deterioration and adhesion failure due to ultraviolet rays. Alternatively, a film or a film obtained by coating a cycloolefin film with one or both surfaces coated with a thermoplastic or thermosetting resin and an ultraviolet absorber may be used. As for the UV-cutting property, the transmittance at a wavelength of 380 nm as measured by a spectrophotometer is preferably 10% or less. More preferably, it is 7% or less.

[Easily adhesive layer]
Next, the said easily bonding layer 2 is demonstrated.
In the present invention, the easy-adhesion layer 2 needs to contain a mixture of a polyolefin resin and a styrene acrylic resin.

  In the present invention, the polyolefin resin constituting the easy-adhesion layer 2 is a resin blended for the purpose of imparting adhesion between the cycloolefin film 1 and the hard coat layer 3. As a result of intensive studies on the resin for an easy adhesion layer having excellent adhesion to both the cycloolefin film 1 and the hard coat layer 3, the present inventors have found that a polyolefin-based resin having excellent flexibility is suitable.

  The polyolefin-based resin used for the easy-adhesion layer 2 in the present invention is not particularly limited, but an ethylene-propylene copolymer and a propylene-butene copolymer are excellent in adhesion to the base material (cycloolefin film). Those constituting the copolymer with two or more types of monomers such as polymers are preferred, and those containing a propylene monomer in the copolymer are particularly preferred. The molecular weight is not particularly limited, but those having a weight average molecular weight in the range of 10,000 to 200,000 are preferable from the viewpoint of the balance between flexibility and adhesion. As such polyolefin resin, for example, commercially available Unistor (trade name: manufactured by Mitsui Chemicals), Surflen (trade name: manufactured by Mitsubishi Chemical), Arrow Base (trade name: manufactured by Unitika Ltd.) , Auroren (trade name: manufactured by Nippon Paper Industries Co., Ltd.) and the like.

  In addition, since this polyolefin-type resin is resin excellent in a softness | flexibility, when an easy-adhesion layer is formed and a film is wound up, it is easy to press-fit. Therefore, it is preferable to prevent pressure-bonding by blending a high hardness resin or inorganic or organic fine particles into the easy-adhesive layer or sticking a protective film on the back surface of the cycloolefin film from the viewpoint of preventing blocking between films.

  In the blending of inorganic or organic fine particles, the blending amount (parts by weight) is in the range of resin / inorganic or organic fine particles forming the easy-adhesion layer 2 = 99.8 / 0.2 to 95.0 / 5.0. It is preferable. When the blending amount of the fine particles exceeds 5.0 parts by weight, it is not preferable because the transparency and the adhesion to the cycloolefin film are lowered. On the other hand, there is a concern that a sufficient effect is not exhibited when the amount of the fine particles is less than 0.2 parts by weight.

  Examples of inorganic fine particles include fine particles such as alumina, zinc oxide, silica, titanium oxide, and cerium oxide. Examples of organic fine particles include fine particles such as acrylic, melamine / formaldehyde condensate, polyethylene, styrene acrylic, and polyester. It can be illustrated. As the particle size, for example, it is preferable to use fine particles of 0.05 μm to 0.20 μm. A particle diameter of less than 0.05 μm is not preferable because the effect of preventing pressure bonding is low. On the other hand, if the particle diameter exceeds 0.20 μm, the effect of preventing further press-bonding cannot be obtained, resulting in an increase in cost, an increase in external haze, and a decrease in transparency, which is not preferable.

  Moreover, in this invention, the styrene acrylic resin contained in the said easily bonding layer 2 is a polymer which contains an acrylic monomer and a styrene monomer alternately or randomly in a structural unit. This styrene acrylic resin is a resin that is blended for the purpose of reducing the difference in shrinkage between the easy-adhesion layer 2 and the hard coat layer 3 and preventing the occurrence of cracks under heat-resistant conditions. It is required to be. In the present invention, as a standard, it is desirable to use a resin having a glass transition temperature of 50 ° C. or higher. Examples of such a styrene acrylic resin include a commercially available ARUFON resin (trade name: manufactured by Toa Gosei Co., Ltd.) and an acrylate resin (trade name: manufactured by Taisei Fine Chemical Co., Ltd.).

In the present invention, the blending ratio (parts by weight) of the polyolefin resin and the styrene acrylic resin contained in the easy-adhesion layer 2 is desirably in the range of 95/5 to 40/60.
When the blending ratio of the polyolefin-based resin exceeds 95 parts by weight, the easy-adhesion layer that is formed is soft and easily stretched. Therefore, due to the difference in shrinkage from the hard coat layer that does not stretch hard, it can be stored at 100 ° C. for 5 minutes. ) And the problem that cracks are likely to occur, and when the hard coat layer is formed on the easy adhesion layer, the coating film hardness (pencil hardness) tends to decrease. On the other hand, when the blending ratio of the polyolefin resin is less than 40 parts by weight, the shrinkage difference between the easy adhesion layer and the hard coat layer is small, and there is no cracking under heat resistant conditions. There is a problem that the adhesion with the film is lowered.

  Further, the coating thickness of the easy-adhesion layer 2 is not particularly limited, but is 0 in a range that does not adversely affect the adhesion between the cycloolefin film and the hard coat layer or the pencil hardness of the hard coat layer. It is desirable that the thickness is 1 μm to 1.0 μm, and more desirably 0.2 μm to 0.6 μm. If the thickness of the easy-adhesion layer 2 is less than 0.1 μm, the adhesion with the hard coat layer is lowered, which is not preferable. On the other hand, when the thickness of the easy-adhesion layer 2 exceeds 1.0 μm, an easy-adhesion layer composed of a resin layer having low hardness is formed in the lower layer of the hard coat layer, and the pencil hardness of the hard coat film is reduced ( For example, the pencil hardness is reduced from pencil hardness H to pencil hardness HB), and cracks are likely to occur under heat resistant conditions.

  The easy-adhesion layer 2 can be blended with a leveling agent for the purpose of improving coatability. For example, a known leveling agent such as a fluorine-based, acrylic-based, siloxane-based, or an adduct or mixture thereof is used. Is possible. The blending amount can be, for example, in the range of 0.03 to 3.0 parts by weight with respect to 100 parts by weight of the resin component of the easy-adhesion layer.

  The easy-adhesion layer 2 can be blended with a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber for the purpose of imparting light-resistant adhesion (preventing adhesion failure due to ultraviolet rays). The blending amount is preferably 0.05 to 10.0 parts by weight with respect to 100 parts by weight of the resin component of the easy-adhesion layer. Particularly preferred is 1.0 to 5.0 parts by weight.

  Further, as other additives to be added to the easy-adhesion layer 2, an antifoaming agent, an antifouling agent, an antioxidant, an antistatic agent, a light stabilizer, and the like are required as long as the effects of the present invention are not impaired. May be blended.

  In the present invention, the easy-adhesion layer 2 is coated on the cycloolefin film 1 with a paint obtained by dissolving and dispersing other additives in an appropriate organic solvent in addition to the polyolefin resin and the styrene acrylic resin. Processed, dried, or then cured and formed. The organic solvent in this case can be appropriately selected according to the solubility of the resin contained therein, and is a solvent that can uniformly dissolve or disperse at least a solid content (resin and other additives), and at the time of coating. The use of an organic solvent having a boiling point of 50 ° C. to 160 ° C. is preferred from the viewpoints of workability and drying properties. Examples of such solvents include aromatic solvents such as toluene, xylene and n-heptane, aliphatic solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and acetic acid. Known organic solvents such as ester solvents such as butyl and methyl lactate, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, and alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol and butanol These can be used alone or in appropriate combinations of several kinds.

  In the present invention, the method for applying the coating material for the easy adhesion layer onto the cycloolefin film 1 includes gravure coating, microgravure coating, fountain bar coating, slide die coating, slot die coating, and screen printing. It can be applied by a known coating method such as a spray coating method. The paint applied on the cycloolefin film 1 is usually dried at a temperature of about 50 to 120 ° C. to remove the solvent, and then cured by applying external energy such as heat energy or ultraviolet rays or electron beams to form a coating film. Form.

[Hard coat layer]
Next, the hard coat layer 3 will be described.
In the present invention, the resin contained in the hard coat layer 3 can be used without particular limitation as long as it is a resin that forms a film, but particularly provides the surface hardness (pencil hardness, scratch resistance) of the hard coat layer. In addition, it is preferable to use an ionizing radiation curable resin in that the degree of crosslinking can be adjusted by the exposure amount of ultraviolet rays, and the surface hardness of the hard coat layer can be adjusted.

  The ionizing radiation curable resin used in the present invention is a transparent resin that is cured by irradiation with ultraviolet rays (hereinafter abbreviated as “UV”) or electron beams (hereinafter abbreviated as “EB”). Although not particularly limited, UV or EB having three or more (meth) acryloyloxy groups in one molecule in order for the coating film hardness and the hard coat layer 3 to form a three-dimensional cross-linked structure. It is preferable to use a polyfunctional acrylate which can be cured. Specific examples of UV or EB curable polyfunctional acrylate having 3 or more (meth) acryloyloxy groups in the molecule include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane ethoxytriacrylate, glycerin propoxy Examples include triacrylate and ditrimethylolpropane tetraacrylate. The polyfunctional acrylate may be used alone or in combination of two or more.

  Furthermore, the ionizing radiation curable resin used in the present invention is preferably a polymer having a weight average molecular weight in the range of 700 to 3600, more preferably a weight average molecular weight in the range of 700 to 3000, and a weight average molecular weight of 700. ˜2400 is more preferred. When the weight average molecular weight is less than 700, the curing shrinkage when cured by UV or EB irradiation is large, and the phenomenon that the hard coat film warps to the hard coat layer surface side (curl) increases, and the subsequent processing steps are performed. Trouble occurs and processing suitability is bad. On the other hand, if the weight average molecular weight exceeds 3600, the flexibility of the hard coat layer increases, but it is not suitable because the hardness is insufficient.

  Further, when the ionizing radiation curable resin used in the present invention has a weight average molecular weight of less than 1500, the number of functional groups in one molecule is desirably 3 or more and less than 10. When the ionizing radiation curable resin has a weight average molecular weight of 1500 or more, the number of functional groups in one molecule is preferably 3 or more and 20 or less. If it is in the said range, curling can be suppressed and generation | occurrence | production of a crack can be suppressed, and an appropriate processing appropriateness can be maintained.

  Moreover, as resin contained in the said hard-coat layer 3, other than the above-mentioned ionizing radiation curable resin, thermoplastic resins, such as polyethylene, a polypropylene, a polystyrene, a polycarbonate, polyester, an acryl, styrene-acryl, a fiber, You may mix | blend thermosetting resins, such as a phenol resin, urea resin, unsaturated polyester, an epoxy, and a silicon resin, in the range which does not impair the hardness of a hard-coat layer, and scratch resistance.

  In addition, as a photopolymerization initiator of an ionizing radiation curable resin contained in the hard coat layer 3, acetophenones such as commercially available IRGACURE 651 and IRGACURE 184 (both trade names: manufactured by BASF), IRGACURE 500 ( Benzophenones such as trade name: BASF) can be used.

  In the present invention, the hard coat layer 3 may contain inorganic oxide fine particles to further improve the surface hardness (scratch resistance). In this case, the average particle diameter of the inorganic oxide fine particles is preferably in the range of 5 to 50 nm, more preferably in the range of 10 to 20 nm. If the average particle size is less than 5 nm, it is difficult to obtain sufficient surface hardness. On the other hand, when the average particle diameter exceeds 50 nm, the gloss and transparency of the hard coat layer are lowered, and the flexibility may be lowered.

  In the present invention, examples of the inorganic oxide fine particles include alumina and silica. Among these, alumina containing aluminum as a main component is particularly suitable because it has a high hardness and can obtain an effect with a smaller amount of addition than silica.

  In the present invention, the content of the inorganic oxide fine particles is preferably 0.1 to 10.0 parts by weight with respect to 100 parts by weight of the solid content of the hard coat layer coating composition. When the content of the inorganic oxide fine particles is less than 0.1 parts by weight, it is difficult to obtain an effect of improving the surface hardness (abrasion resistance). On the other hand, if the content exceeds 10.0 parts by weight, the haze increases, which is not preferable.

For the hard coat layer 3, a leveling agent can be used for the purpose of improving coatability. For example, a known leveling agent such as fluorine-based, acrylic-based, siloxane-based, or an adduct or mixture thereof is used. Is possible. The blending amount can be in the range of 0.03 to 3.0 parts by weight with respect to 100 parts by weight of the solid content of the resin of the hard coat layer. In addition, in touch panel applications and the like, adhesion to the cover glass (CG), transparent conductive member (TSP), liquid crystal module (LCM), etc. of the touch panel terminal using an optical transparent adhesive OCR is required. In this case, it is preferable to use an acrylic leveling agent or a fluorine leveling agent having a high surface free energy (approximately 40 mJ / cm ² or more).

  As other additives to be added to the hard coat layer 3, as long as the effects of the present invention are not impaired, an antifoaming agent, a surface tension adjusting agent, an antifouling agent, an antioxidant, an antistatic agent, an ultraviolet absorber, light You may mix | blend a stabilizer etc. as needed.

  The hard coat layer 3 is formed by applying and drying a paint obtained by dissolving and dispersing a polymerization initiator, other additives and the like in an appropriate solvent in addition to the ionizing radiation curable resin. Formed. The solvent can be appropriately selected depending on the solubility of the resin to be blended, and may be any solvent that can uniformly dissolve or disperse at least solids (resin, polymerization initiator, and other additives). Examples of such solvents include aromatic solvents such as toluene, xylene and n-heptane, aliphatic solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and acetic acid. A known organic solvent such as an ester solvent such as butyl or methyl lactate, a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone, or an alcohol solvent such as methanol, ethanol, isopropyl alcohol, or n-propyl alcohol. Or it can also be used in combination of several kinds as appropriate.

  The coating method of the hard coat layer 3 is not particularly limited, but gravure coating, micro gravure coating, fountain bar coating, slide die coating, slot die coating, screen printing method, spray coating method, etc. After coating by the known coating method, it is usually dried at a temperature of about 50 to 120 ° C.

Further, the hard coat layer 3 preferably satisfies the following conditions.
Conditions: A film is formed on a polyethylene terephthalate film by forming a hard coat layer made of the above-mentioned ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² so as to form a 2 μm thick coating film. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation until cracks occur in the coating film is 8% or more and 45% or less.

By satisfy | filling the said conditions, the above-mentioned curl is suppressed and the hard-coat layer 3 can obtain the hard-coat film which is excellent in processability.
In order for the hard coat layer 3 to satisfy the above conditions, examples of the ionizing radiation curable resin contained in the hard coat layer 3 include EBECRYL-5129 (manufactured by Daicel Ornex Co., Ltd.), NK Oligo U-6LPA (Shin Nakamura). Preferable examples include Chemical Industry Co., Ltd., Art-Resin UN-908 (Negami Kogyo Co., Ltd.), and Unidic 17-806 (DIC Corporation).

  The coating thickness of the hard coat layer 3 is not particularly limited, but is preferably in the range of 1.0 μm to 15.0 μm, for example. If the coating thickness is less than 1.0 μm, it is difficult to obtain the required surface hardness. On the other hand, when the coating film thickness exceeds 15.0 μm, curling is strongly generated and handling properties are lowered in the manufacturing process and the like, which is not preferable. The coating thickness of the hard coat layer 3 can be measured by actually measuring with a micrometer.

  In the present invention, the hard coat layer coating containing the ionizing radiation curable resin is applied to a cycloolefin film having an easy-adhesion layer, dried, and then irradiated with UV or EB to cause photopolymerization and hard coating. A coating film having excellent properties can be obtained. In particular, a hard coat layer having a pencil hardness of B to 2H specified in JIS K5600-5-4 is preferable.

  As described above in detail, the hard coat film of the present invention is provided with a hard coat layer on at least one side of a cycloolefin film via an easy adhesion layer, and the easy adhesion layer is a mixture of a polyolefin resin and a styrene acrylic resin. By containing, the adhesiveness of a cycloolefin film and a hard-coat layer can be improved, and it is excellent in especially the time-dependent adhesiveness on normal conditions and heat-and-moisture resistant conditions. Moreover, even when it preserve | saves on heat resistant conditions by reducing the shrinkage | contraction difference of an easily bonding layer and a hard-coat layer, generation | occurrence | production of a crack can be prevented. Furthermore, curling can be suppressed by controlling the elongation (elongation rate) of the hard coat layer within a predetermined range.

EXAMPLES Next, although an Example and a comparative example are given and this invention is explained in full detail concretely, this invention is not limited to a following example.
Unless otherwise specified, “parts” and “%” described below represent “parts by weight” and “% by weight”, respectively.

[Example 1]
<Preparation of easy adhesion layer paint>
First, 60 parts of styrene acrylic resin “ARUFON UG-4070 (trade name)” (solid content 100%, manufactured by Toa Gosei Co., Ltd., glass transition temperature 58 ° C.) was stirred into 140 parts of ethyl acetate using a stirrer. While adding a small amount, the resin was dissolved to prepare a solution having a concentration of 30%.
Next, 70 parts of polyolefin resin “Surflen P-1000 (trade name)” (solid content 20%, manufactured by Mitsubishi Chemical Corporation) and the above styrene acrylic resin “ARUFON UG-4070 (trade name)” (solid content 30 %) 20 parts, and diluted with butyl acetate / toluene = 85/15 (% by weight) to a solid content concentration of 5% to prepare an easy adhesion layer coating material.

<Preparation of hard coat layer paint>
100 parts of urethane acrylate ultraviolet curable resin “Shikou UV-7630B (trade name)” (solid content 100%, (meth) acryloyloxy group number: 6, weight average molecular weight: 2200, manufactured by Nippon Synthetic Chemical Co., Ltd.) Irgacure 184 (photopolymerization initiator, manufactured by BASF) 3.5 parts, hindered amine light stabilizer “TINUVIN 292 (trade name)” (manufactured by BASF) 2.5 parts, and leveling agent RS75 (fluorine-based) Dilute 0.3 parts of leveling agent (manufactured by DIC Corporation) with butyl acetate / n-propyl alcohol = 50/50 (parts by weight) until the solid content concentration in the paint of the UV curable resin becomes 45% and stir sufficiently Thus, a hard coat layer paint was prepared.
Using the hard coat layer coating, a hard coat layer made of an ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² is formed on a polyethylene terephthalate film so as to be a 2 μm thick coating film. Create a film. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation rate until cracks occurred in the coating film was 11.5%.

<Preparation of hard coat film>
Apply the above-mentioned easy-adhesion layer paint using a bar coater on one side of a ZEONOR film ZF14 (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 60 μm as a cycloolefin film, and dry and solidify in a 90 ° C. drying oven for 1 minute Then, an easy-adhesion layer having a coating film thickness of 0.3 μm was formed to obtain a film with an easy-adhesion layer.
Next, the above-mentioned hard coat layer paint is applied on the easy-adhesion layer of the film with the easy-adhesion layer using a bar coater and dried with hot air in a drying furnace at 80 ° C. for 1 minute to obtain a coating thickness of 5. A 0 μm coating layer was formed. This was cured using a UV irradiation apparatus set at a height of 60 mm from the coated surface at a UV irradiation amount of 150 mJ / cm ² to form a hard coat layer, and a hard coat film of this example was produced.

[Example 2]
A hard coat film was obtained in the same manner as in Example 1 except that the blending part of the polyolefin resin and the styrene acrylic resin in the easy-adhesion layer of Example 1 was 95 parts / 5 parts.

[Example 3]
A hard coat film was obtained in the same manner as in Example 1 except that the blending part of the polyolefin resin and the styrene acrylic resin in the easy adhesion layer of Example 1 was 40 parts / 60 parts.

[Example 4]
A hard coat film was obtained in the same manner as in Example 1 except that the coating thickness of the easy-adhesion layer in Example 1 was 0.1 μm.

[Example 5]
A hard coat film was obtained in the same manner as in Example 1 except that the thickness of the easy-adhesion layer in Example 1 was 1.0 μm.

[Example 6]
Other than using “polyolefin resin unistal P-901 (trade name)” (solid content 22%, manufactured by Mitsui Chemicals, Inc.) instead of the polyolefin resin surflene P-1000 used in the easy-adhesion layer of Example 1. Obtained a hard coat film in the same manner as in Example 1.

[Example 7]
A hard coat film was obtained in the same manner as in Example 1 except that the cycloolefin film of Example 1 was changed to “ARTON FILM FEKP100 (trade name)” (manufactured by JSR Corporation) having a thickness of 100 μm.

[Example 8]
“UA-306H (trade name)” (solid content 100%, (meth) acryloyloxy group number: 3, in place of the urethane acrylate ultraviolet curable resin “purple light UV-7630B” used in the hard coat layer of Example 1 A hard coat film was obtained in the same manner as in Example 1 except that weight average molecular weight: 732, manufactured by Kyoeisha Chemical Co., Ltd.) was used.
A hard coat layer made of an ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² on a polyethylene terephthalate film using the hard coat layer coating material of this example becomes a 2 μm thick coating film. A film thus formed is prepared. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation rate until cracks occurred in the coating film was 8.2%.

[Example 9]
A hard coat film was obtained in the same manner as in Example 1 except that the blending part of the polyolefin resin and the styrene acrylic resin in the easy-adhesion layer of Example 1 was 97 parts / 3 parts.

[Example 10]
A hard coat film was obtained in the same manner as in Example 1 except that the blending part of the polyolefin-based resin and the styrene-acrylic resin in the easy adhesion layer of Example 1 was 37 parts / 63 parts.

[Example 11]
“ARUFON UG-4035 (trade name)” (solid content 30%, glass transition temperature 52 ° C., Toa) instead of the styrene acrylic resin “ARUFON UG-4070 (trade name)” used in the easy-adhesion layer of Example 2 A hard coat film was obtained in the same manner as in Example 2 except that Synthetic Co., Ltd. was used.

[Example 12]
“ARUFON UG-4040 (trade name)” (solid content 30%, glass transition temperature 63 ° C., Toa) instead of styrene acrylic resin “ARUFON UG-4070 (trade name)” used in the easy adhesion layer of Example 2 A hard coat film was obtained in the same manner as in Example 2 except that Synthetic Co., Ltd. was used.

[Example 13]
“EBECRYL-5129 (trade name)” (100% solids, (meth) acryloyloxy) instead of the urethane acrylate UV curable resin “purple UV-7630B (trade name)” used in the hard coat layer of Example 1 A hard coat film was obtained in the same manner as in Example 1 except that base number: 6, weight average molecular weight: 800, manufactured by Daicel Ornex Co., Ltd. was used.
A hard coat layer made of an ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² on a polyethylene terephthalate film using the hard coat layer coating material of this example becomes a 2 μm thick coating film. A film thus formed is prepared. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation rate until cracks occurred in the coating film was 8.5%.

[Example 14]
“NK Oligo U-6LPA (trade name)” (100% solid content, (meta)) instead of the urethane acrylate UV curable resin “Shikou UV-7630B (trade name)” used in the hard coat layer of Example 1 A hard coat film was obtained in the same manner as in Example 1 except that the number of acryloyloxy groups: 6, weight average molecular weight: 760, manufactured by Shin-Nakamura Chemical Co., Ltd. was used.
A hard coat layer made of an ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² on a polyethylene terephthalate film using the hard coat layer coating material of this example becomes a 2 μm thick coating film. A film thus formed is prepared. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation rate until cracks occurred in the coating film was 44.5%.

[Comparative Example 1]
The same as Example 1 except that the blending number of the polyolefin resin and the styrene acrylic resin of the easy adhesion layer of Example 1 was 100 parts / 0 part (that is, the styrene acrylic resin was not used). Thus, a hard coat film was obtained.

[Comparative Example 2]
The same procedure as in Example 1 except that the blending part of the polyolefin resin and the styrene acrylic resin in the easy adhesion layer of Example 1 was 0 part / 100 parts (that is, the polyolefin resin was not used). To obtain a hard coat film.

[Comparative Example 3]
“Art-Resin UN-904 (trade name)” (solid content 100%, (Metal) instead of the urethane acrylate-based ultraviolet curable resin “purple UV-7630B (trade name)” used in the hard coat layer of Example 1 ) A hard coat film was obtained in the same manner as in Example 1 except that acryloyloxy group number: 10, weight average molecular weight: 4900, manufactured by Negami Industrial Co., Ltd. was used.
A hard coat layer made of an ionizing radiation curable resin cured with an ultraviolet light amount of 50 to 1000 mJ / cm ² on a polyethylene terephthalate film using the hard coat layer paint of this comparative example becomes a 2 μm thick coating film. A film thus formed is prepared. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation rate until cracks occurred in the coating film was 7.8%.

The hard coat films of Examples and Comparative Examples produced as described above were evaluated for the following items, and the results are summarized in Table 1.
(1) Film thickness The formation thickness of the easy-adhesion layer and the hard coat layer was measured using Thin-Film Analyzer F20 (trade name) (manufactured by FILMETRICS).

(2) Transparency The total light transmittance was measured by the test method shown in JIS K7136 for the hard coat films prepared in each Example and Comparative Example.

(3) Adhesion (initial adhesion and adhesion over time)
The adhesion was evaluated according to JIS-K5600-5-6. In addition, in order to confirm the adhesion between the easy-adhesion layer and the cycloolefin film and the adhesion between the easy-adhesion layer and the hard coat layer, the easy-adhesion layer and the cycloolefin were formed by forming an easy-adhesion layer on the cycloolefin film. The adhesion with the film was confirmed, and the adhesion between the easy adhesion layer and the hard coat layer was evaluated by forming an easy adhesion layer and a hard coat layer on the cycloolefin film.
First, the adhesion (initial adhesion) between the easy-adhesion layer and the cycloolefin film is 1 mm using a cross-cut peel test jig under normal conditions, that is, constant temperature and humidity conditions (23 ° C., 50% RH). 100 cross-cuts of ² were prepared, Sekisui Chemical Co., Ltd. adhesive tape No. 252 was applied on it, pressed evenly with a spatula, then peeled in the direction of 90 degrees, leaving an easily adhesive layer The number was evaluated in four stages.
Next, the adhesion (initial adhesion) between the easy-adhesion layer and the hard coat layer was evaluated in the same manner.
The evaluation criteria are as follows, and ◎ and ○ evaluation products were judged to have passed.
Evaluation criteria ◎: 100 pieces ○: 99 to 95 pieces △: 94 to 50 pieces ×: 49 to 0 pieces

  Furthermore, with respect to the adhesion over time, each hard coat film (with a hard coat layer coated on the easy-adhesion layer) prepared in the examples and comparative examples was suspended in a sample in a blow dryer at a temperature of 90 ° C. After being stored on the implement and stored for 30 days, a sample was taken out and evaluated for adhesion according to JIS-K5600-5-6 described above. The evaluation criteria are the same as in the case of the above initial adhesion. This time-dependent adhesion was evaluated at all the interfaces between the base material, the easy-adhesion layer, and the hard coat layer.

(4) Heat-resistant cracks Each hard coat film produced in Examples and Comparative Examples was suspended and stored for 5 minutes using a sample holder in a dryer at 100 ° C, and then the hard coat film sample was taken out and checked for cracks. Visual evaluation was made. The degree of occurrence of cracks was evaluated according to the following criteria. ○ The evaluation product was considered to have good heat-resistant cracks.
Evaluation criteria ○: No crack occurred ×: Crack occurred

(5) Scratch resistance About each hard coat film produced by the Example and the comparative example, the hard-coat layer surface was made into steel wool # 0000 by the test method according to JIS-K5600-5-10, and 1 kg of loads were applied. 10 times reciprocating friction was applied, and the degree of scratching was evaluated according to the following criteria. ○ Although the evaluation product has good scratch resistance, the evaluation product can also be used as a product.
Evaluation criteria ○: No scratches occurred. Δ: Some scratches occur. X: Innumerable scratches occur.

(6) Pencil hardness About the hard coat film produced by each Example and the comparative example, pencil hardness was measured by the test method according to JISK5600-5-4. The hardness without scratches on the surface was indicated.

(7) Curl characteristics (curl height)
About the hard coat film produced by each Example and the comparative example, the test piece of the square rhombus shape of 10 cm of one side based on the application direction (MD direction of illustration) was cut out like FIG. 2, and the hard coat layer surface was set | placed on the horizontal surface. Set up and store for 30 minutes in a 23 ° C, 50% RH environment, then measure the height of the four vertices (A, B, C, D) that are warped from the horizontal plane, and calculate the average value. The curl height was evaluated based on the following criteria. Δ or more is set as a practically acceptable range.
Evaluation criteria A: Curl height is 30 mm or less B: Curl height is more than 30 mm, 40 mm or less Δ: Curl height exceeds 40 mm, but does not form a cylinder.
X: The curl is large, warps from each vertex, and the test piece becomes cylindrical.

As is apparent from the results of Table 1 above, according to the examples of the present invention, the cycloolefin film and the hard coat layer were formed by the easy adhesion layer containing (in combination with) the mixture of the polyolefin resin and the styrene acrylic resin. Adhesiveness with both can be improved, and a hard coat film having excellent adhesion over time under normal conditions and heat-and-moisture resistance conditions and free from cracks under heat-resistant conditions can be obtained. In addition, when an ionizing radiation curable resin contained in the hard coat layer has a resin having three or more (meth) acryloyloxy groups in one molecule, it has excellent surface hardness (abrasion resistance, pencil hardness). A coated film can be obtained. Furthermore, by using a specific ionizing radiation curable resin for the hard coat layer and controlling the elongation (elongation rate) of the hard coat layer within a predetermined range, a curl is sufficiently suppressed and a hard coat film excellent in processing suitability is obtained. (Especially Examples 13 and 14).
Furthermore, when the blending ratio (parts by weight) of the polyolefin resin and the styrene acrylic resin in the easy-adhesion layer is in the range of 95/5 to 40/60, the effects of the present invention are more remarkably exhibited. Is shown.

  On the other hand, in Comparative Examples 1 and 2 in which the polyurethane resin and the styrene acrylic resin are not used in combination in the easy-adhesion layer, there is a problem that the crack is likely to occur under heat resistant conditions (Comparative Example 1), There existed a problem (comparative example 2) in which adhesiveness and the time-dependent adhesiveness under heat-and-moisture-resistant conditions were inferior. In Comparative Example 3 in which an ionizing radiation curable resin having a weight average molecular weight of 4900 is used for the hard coat layer, cracks are likely to occur under heat resistant conditions, and the curl is large and the processing suitability is poor.

1 Cycloolefin film 2 Easy adhesion layer 3 Hard coat layer 10 Hard coat film

Claims (5)

A hard coat film in which a hard coat layer is provided on at least one side of a cycloolefin film via an easy adhesion layer,
The easy adhesion layer contains a mixture of a polyolefin resin and a styrene acrylic resin, and the hard coat layer contains an ionizing radiation curable resin having a weight average molecular weight of 700 to 3600. Coat film.   The hard coat film according to claim 1, wherein a blending ratio (parts by weight) of the polyolefin resin and the styrene acrylic resin in the easy-adhesion layer is in a range of 95/5 to 40/60. .   3. The hard coat film according to claim 1, wherein the ionizing radiation curable resin contains a polyfunctional acrylate having three or more (meth) acryloyloxy groups in one molecule. The hard coat film according to any one of claims 1 to 3, wherein the hard coat layer satisfies the following conditions.
Conditions: A film is formed on a polyethylene terephthalate film by forming a hard coat layer made of the above-mentioned ionizing radiation curable resin cured with an ultraviolet light quantity of 50 to 1000 mJ / cm ² so as to form a 2 μm thick coating film. Next, a test piece having a width of 15 mm and a length of 150 mm was prepared from the film, and the test piece was subjected to a tensile test at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50% RH. The elongation until cracks occur in the coating film is 8% or more and 45% or less.   The hard coat film according to any one of claims 1 to 4, wherein the easy adhesion layer has a thickness in a range of 0.1 µm to 1.0 µm.

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